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| United States Patent |
6,054,106
|
|
Thompson
, et al.
|
April 25, 2000
|
Magnesiosilicates
Abstract
Novel magnesiosilicate compounds for use in detergent compositions and as
water softeners have a calcium binding capacity of at least 10 mg CaO per
gram, a magnesium binding capacity of at least 10 mg MgO per gram and a
calcium binding rate of no more than 300 seconds, all at room temperature.
The compounds have a stuffed silica polymorph-related structure or a
layered structure with a broad X-ray powder diffraction peak at a
d-spacing of between 11 and 17 .ANG.. The compounds have an anhydrous
composition M.sub.a Mg.sub.b Al.sub.c Si.sub.1-(b+c) O.sub.d, where
M--alkali, 0.0<a<2.0, 0.0<b<0.7, 0.0.ltoreq.c.ltoreq.0.3, 1.15<d<3.0, c<b,
and partial substitution of M, Mg, Al and Si is permitted. The compounds
are prepared by solid state reaction or aqueous reaction of starting
material such as magnesiosilicate mineral with alkali oxide-containing
reagent under relatively mild conditions or by treating a magnesiosilicate
compound having a stuffed silica polymorph-related structure with aqueous
solution.
| Inventors:
|
Thompson; John G. (Australian Capital Territory, AU);
Melnitchenko; Alexandra (Australian Capital Territory, AU);
Palethorpe; Stephen R. (Australian Capital Territory, AU);
Lobo; Charlene J. (Australian Capital Territory, AU)
|
| Assignee:
|
The Australian National University (Australian Capital Territory, AU)
|
| Appl. No.:
|
043087 |
| Filed:
|
June 10, 1998 |
| PCT Filed:
|
September 13, 1996
|
| PCT NO:
|
PCT/AU96/00576
|
| 371 Date:
|
June 10, 1998
|
| 102(e) Date:
|
June 10, 1998
|
| PCT PUB.NO.:
|
WO97/10179 |
| PCT PUB. Date:
|
March 20, 1997 |
Foreign Application Priority Data
| Current U.S. Class: |
423/331; 423/326; 423/328.2; 423/332; 510/507; 510/511; 510/531; 510/532 |
| Intern'l Class: |
C01B 033/22; C01B 033/32; C11D 003/08 |
| Field of Search: |
423/331,332,328.2
510/276,507,511,531,532
|
References Cited
U.S. Patent Documents
| 4049780 | Sep., 1977 | Neumann | 423/331.
|
| 4054537 | Oct., 1977 | Wright et al. | 423/331.
|
| 4430249 | Feb., 1984 | Gate.
| |
| 4542002 | Sep., 1985 | Corma et al. | 423/331.
|
| 4585642 | Apr., 1986 | Rieck | 423/333.
|
| 4664839 | May., 1987 | Rieck.
| |
| 4737306 | Apr., 1988 | Wichelhaus et al. | 423/331.
|
| 4749676 | Jun., 1988 | Blumenthal et al. | 502/251.
|
| 4820439 | Apr., 1989 | Rieck.
| |
| 4950310 | Aug., 1990 | Rieck et al.
| |
| 4987106 | Jan., 1991 | Mizutani et al. | 501/147.
|
| 5308596 | May., 1994 | Kotzian et al. | 423/333.
|
| 5559070 | Sep., 1996 | Torii et al. | 423/326.
|
| Foreign Patent Documents |
| 0 209 840 A2 | Jan., 1987 | EP.
| |
| 0 384 070 A2 | Aug., 1990 | EP.
| |
| 0 543 443 A2 | May., 1993 | EP.
| |
| 0 549 323 A1 | Jun., 1993 | EP.
| |
| 0 550 048 A1 | Jul., 1993 | EP.
| |
| 0 565 364 A1 | Oct., 1993 | EP.
| |
| 0 630 855 A2 | Dec., 1994 | EP.
| |
| 0 627 383 A1 | Dec., 1994 | EP.
| |
| 43 23 527 A1 | Jan., 1995 | DE.
| |
| 58-181718 | Oct., 1983 | JP.
| |
| 2-271910 | Nov., 1990 | JP.
| |
| 8-059226 | Mar., 1996 | JP.
| |
| 998822 | Jul., 1965 | GB.
| |
| 92/18594 | Oct., 1992 | WO.
| |
| 94/03572 | Feb., 1994 | WO.
| |
| 95/29978 | Nov., 1995 | WO.
| |
| 95/34505 | Dec., 1995 | WO.
| |
| 96/12674 | May., 1996 | WO.
| |
Other References
Shannon, R.D., "Ionic Conductivity in Sodium Magnesium Silicates," Phys.
Chem. Minerals, 4:139-148 (1979) (No Month).
Foris et al., "Crystal Data for Na.sub.4 Mg.sub.2 Si.sub.3 O10," J. App.
Cryst., 12:405-406 (1979) (No Month).
Berezhnoi et al., "Characteristics of Multicomponent High-Basic Silicates
of the System Na.sub.2 O-K.sub.2 O-CaO-MgO-SiO.sub.2," Izvestiya Akademii
Nauk SSSR, Neorganicheskie Materialy, 12(9):1653-1658 (Sep. 1976).
Roedder, E.W., "The System R.sub.2 O-MgO-SiO.sub.2," Amer. J. Sci.,
249:224-281 (1951) (No Month).
Buerger M.J., "The Stuffed Derivatives of the Silica Structures," American
Mineralogist, 39:600-614 (1954) (No Month).
|
Primary Examiner: Bell; Mark L.
Assistant Examiner: Sample; David
Attorney, Agent or Firm: Flehr Hohbach Test Albritton & Herbert LLP, Brezner; David J.
Claims
We claim:
1. A magnesiosilicate compound having a calcium binding capacity (CBC) of
at least mg CaO per gram at room temperature, a magnesium binding capacity
(MBC) of at least mg MgO per gram at room temperature, a calcium binding
rate (CBR) of no more than 300 seconds at room temperature, being the time
taken to remove half of the Ca.sup.2+ from a .about.100 ppm Ca.sup.2+
solution at a loading of 3 g per liter, and having a stuffed silica
polymorph-related structure.
2. A magnesiosilicate compound according to claim 1 which has a composition
in anhydrous form given by M.sub.a Mg.sub.b Al.sub.c
Si.sub.1-(b+c)O.sub.d, where M=alkali, optionally partially substituted by
H or NH.sub.4 ; where 0.0<a<2.0, 0.0<b<0.7, 0.0.ltoreq.c.ltoreq.0.3, and
1.15<d<3.0; where c<b; where there may be partial substitution of the
atoms (Mg+Al+Si) by one or more other elements T selected from the group
B, Be, Zn, Ga, Fe, Ge, As and P such that T/(Mg+Al+Si)<0.1 and Mg>0; where
there may be partial substitution of the interstitial atoms M by one or
more other elements A selected from the group alkaline earth, transition
metal and rare earth elements such that A/M<0.2; and where impurity
minerals or compounds which are not integrated into the structure are not
accounted for in the composition.
3. A magnesiosilicate compound according to claim 2 where 0.4<a<1.4,
0.2<b<0.6, 0.0.ltoreq.c.ltoreq.0.2, and 1.5<d<2.5; and where
T/(Mg+Al+Si)<0.05.
4. A magnesiosilicate compound according to claim 3 where 0.6<a<1.3,
0.35<b<0.6, 0.0.ltoreq.c.ltoreq.0.1, and 1.65<d<2.25; and where
T/(Mg+Al+Si)<0.02.
5. A magnesiosilicate compound according to claim 2 where Mg/Ca .ltoreq.100
and Si/(Mg+Ca)<1.4.
6. A magnesiosilicate compound according to claim 1 wherein M is selected
from one or both of K and Na.
7. A magnesiosilicate compound according to claim 1 which has a stuffed
silica polymorph-related structure, where the dominant X-ray powder
diffraction peaks or groups of peaks occur simultaneously at a d-spacing
of 4.30.+-.0.15 .ANG. and at a d-spacing of 2.64.+-.0.22 .ANG..
8. A magnesiosilicate compound according to claim 1 which has a stuffed
silica polymorph-related structure, where the dominant X-ray powder
diffraction peak or group of peaks occurs at a d-spacing of 2.73.+-.0.15
.ANG. and a weaker peak or group of peaks at a d-spacing of 4.44.+-.0.10
.ANG..
9. A magnesiosilicate compound according to claim 1 which has a stuffed
silica polymorph-related structure, where the dominant X-ray powder
diffraction peak occurs at a d-spacing of 3.11.+-.0.20 .ANG..
10. A magnesiosilicate compound according to claim 1 which has a CBC of at
least 50 mg CaO per gram at room temperature.
11. A magnesiosilicate compound according to claim 1 which has an MBC of at
least 40 mg MgO per gram at room temperature.
12. A magnesiosilicate compound according to claim 1 which has a CBR of no
more than 100 seconds at room temperature.
13. A magnesiosilicate compound according to claim 1 which has an oil
adsorption (OA) of at least 50 g oil per 100 g of anhydrous material.
14. A magnesiosilicate compound according to claim 1 which is prepared
using magnesiosilicate mineral starting material.
15. A magnesiosilicate compound according to claim 1 which has a CBC of at
least 150 mg CaO per gram at room temperature.
16. A magnesiosilicate compound according to claim 1 which has an MBC of at
least 140 mg MgO per gram at room temperature.
17. A magnesiosilicate compound according to claim 1 which has a CBR of no
more then 10 seconds at room temperature.
18. A magnesiosilicate compound according to claim 1 which has an oil
adsorption (OA) of at least 100 g oil per 100 g of anhydrous material.
19. A process for the preparation of a magnesiosilicate compound according
to claim 1 and having a stuffed silica polymorph-related structure, which
comprises subjecting a magnesiosilicate starting material, or a
combination of magnesium oxide- and silicon oxide-containing reagents, to
a solid state reaction with an alkali oxide- containing reagent.
20. A process according to claim 19 in which the reaction is performed at a
temperature of about 1000.degree. C. or less.
21. A process according to claim 20 in which the reaction is performed in a
temperature range of about 450 to about 800.degree. C.
22. A process according to claim 19 wherein the alkali oxide-containing
reagent decomposes in air at a temperature below about 1000.degree. C. to
give alkali oxide.
23. A process according to claim 22 wherein the alkali oxide- containing
reagent is selected from one or more of the group bicarbonate, carbonate,
carboxylate, nitrate and hydroxide.
24. A process according to claim 19 wherein the alkali oxide-containing
reagent contains one or both K and Na.
25. A process according to claim 19 wherein the magnesiosilicate starting
material comprises a phyllosilicate mineral.
26. A process according to claim 25 wherein the phyllosilicate mineral is
selected from one or both of talc and saponite.
27. A magnesiosilicate compound according to claim 1 useful as a water
softener.
28. A magnesiosilicate compound according to claim 1 useful as a detergent
builder.
29. A detergent composition containing a magnesiosilicate compound
according to claim 1 and a surfactant.
30. A moulded body comprising magnesiosilicate compound according to claim
1, optionally further comprising a binder.
31. A process for the preparation of a magnesiosilicate compound having a
layered structure with a characteristic broad X-ray powder diffraction
peak occurring at a d-spacing of between 11 and 17 .ANG., which comprises
treating a magnesiosilicate compound having a calcium binding capacity
(CBC) of at least mg CaO per gram at room temperature, a magnesium binding
capacity (MBC) of at least 10 mg MgO per gram at room temperature, a
calcium binding rate (CBR) of no more than 300 seconds at room
temperature, being the time taken to remove half of the Ca.sup.2+ from a
.about.100 ppm Ca.sup.2+ solution at a loading of 3 g per liter, and
having a stuffed silica polymorph-related structure with aqueous solution.
32. A process according to claim 31 wherein the magnesiosilicate compound
having a stuffed silica polymorph-related structure has a CBC of at least
20 mg CaO per gram at room temperature, an MBC of at least 15 mg MgO per
gram at room temperature, and a CBR of no more then 200 seconds at room
temperature.
33. A process according to claim 31 in which the magnesiosilicate compound
having a stuffed silica polymorph-related structure is dispersed in the
aqueous solution, and wherein residual solid is separated from supernatant
liquid and dried.
34. A process according to claim 33 wherein the dispersing and separating
steps take no more than about 20 minutes.
35. A process according to claim 33 wherein the separated residual solid is
dried at less than about 100.degree. C.
36. A process according to claim 33 wherein the dispersing and separating
steps take less than about 10 minutes.
37. A process according to claim 33 wherein the separated residual solid is
dried at less than about 60.degree. C.
Description
TECHNICAL FIELD
This invention relates to magnesiosilicate compounds and is particularly
concerned with such compounds which can be used as water softeners or
detergent builders. The magnesiosilicate compounds may have other uses,
including, for example, separating heavy metals and other contaminants.
BACKGROUND ART
In recent years there has been a trend towards low-phosphate and
phosphate-free detergent formulations. To this end a number of
non-phosphate detergent builders and water softeners have been developed.
Na zeolite A, a synthetic aluminosilicate of composition NaAlSiO.sub.4,
has been used in high volumes for many years and is as effective as sodium
tripolyphosphate (STPP) at removing calcium but not as effective at
removing magnesium. This aluminosilicate zeolite has recently been joined
by zeolite P (European Patent Applications 0 384 070 and 0 565 364) as a
commercially used builder which shows enhanced exchange kinetics.
Alternative technologies are based on soluble silicates (amorphous and
crystalline) which soften water effectively and generally show better
magnesium removal than Na zeolite A. A crystalline layered sodium silicate
SKS-6 (Na.sub.2 Si.sub.2 O.sub.5), which is used commercially, has also
been developed by Hoechst AG and is described in U.S. Pat. Nos. 4,664,839,
4,820,439, 4,950,310 and 5,308,596. Also, crystalline sodium silicates
with the kanemite structure and composition NaHSi.sub.2 O.sub.5.xH.sub.2 O
have recently been developed by Hoechst AG, as described in European
Patent Application 0 627 383.
Synthetic alkali magnesiosilicates having an anhydrous composition of
xM.sub.2 O.ySiO.sub.2.zM'O where M represents Na and/or K; M' represents
Ca and/or Mg; y/x is 1.4 to 2.1; z/x is 0.001 to 1.0; K/Na in M.sub.2 O is
0 to 80; and Mg/Ca in M'O is 0 to 100 have recently been proposed by Kao
Corporation in European Patent Application 0 630 855. These materials,
which have a chain silicate structure as described in European Patent
Application 0 550 048, are shown to have high calcium binding capacity and
to have utility as water softeners and as alkali adjusting agents. In
addition, they are described as particularly useful for their good
moisture resistance (Japanese Patent Application Kokai 07,330,325).
Synthetic alkali magnesiosilicate compounds with the general formula
M.sub.2-2x Mg.sub.1-x Si.sub.1+x O.sub.4, where M is an alkali metal, have
been reported previously, as discussed below. However, these highly
crystalline compounds have not been recognised as having properties that
enable them to be used as water softeners or detergent builders.
The compounds Na.sub.2 MgSiO.sub.4 (R. D. Shannon, Phys. Chem. Miner. 4,
139-148, 1979), Na.sub.4 Mg.sub.2 Si.sub.3 O.sub.10 (C. M. Foris et al. J.
Appl. Cryst. 12, 405-406, 1979) and K.sub.2 MgSiO.sub.4 (E. W. Roedder,
Am. J. Sci., 249, 224248, 1951; A. S. Berezhnoi et al. Izvestiya Akademiii
Nauk SSSR, Neorganicheskie Materialy 12, 1653-1658, 1976) have all been
described as having structures closely related to that of the silica
polymorph, cristobalite (see FIG. 1). It has also been proposed (E. W.
Roedder, Am. J. Sci., 249, 224-248, 1951) that in terms of the general
formula M.sub.2-2x Mg.sub.1-x Si.sub.1+x O.sub.4, when M=K and x=0.5, i.e.
KMg.sub.0.5 Si.sub.1.5 O.sub.4, a compound is formed which has a structure
closely related to that of the silica polymorph, tridymite (see FIG. 2).
Tridymite and cristobalite both have the composition SiO.sub.2 and comprise
a 3-dimensional framework of corner-connected SiO.sub.4 tetrahedra. They
are classified as framework silicates or tectosilicates.
By analogy with alkali aluminosilicate analogues, the cristobalite- and
tridymite-related compounds described above can also be described as
stuffed derivatives of the cristobalite and tridymite structures (M. J.
Buerger, American Mineralogist 39 600-614, 1954), and therefore as stuffed
silica polymorph-related structures, in that up to half of the silicon
cations in the silicate framework in each case are replaced by magnesium
cations. Alkali cations, which are required for charge balance (Si.sup.4+
<-->Mg.sup.2+ +2M.sup.+, M=alkali) occupy the interstices in the
respective frameworks (see FIGS. 1 and 2)--hence the descriptions "stuffed
cristobalite" and "stuffed tridymite". Other stuffed silica
polymorph-related structures include "stuffed quartz".
All of the above alkali magnesiosilicate compounds having stuffed silica
polymorph-related structures were prepared from synthetic reagents and
under reaction conditions that promoted the formation of very well
crystallised and ordered materials.
SUMMARY OF THE INVENTION
We have now discovered that some forms of magnesiosilicate compounds not
previously described, including some having a stuffed silica
polymorph-related structure, can have advantageous water softening and
detergency building properties, as measured in terms of a combination of
their calcium binding capacities, their magnesium binding properties and
their calcium binding rates. The aforementioned known magnesiosilicate
structures having a stuffed silica polymorph-related structure may have
had some but not all of these properties.
According to the present invention there is provided a magnesiosilicate
compound having a calcium binding capacity (CBC) of at least 10 mg CaO per
gram at room temperature, a magnesium binding capacity (MBC) of at least
mg MgO per gram at room temperature. and a calcium binding rate (CBR) of
no more than 300 seconds at room temperature, being the time taken to
remove half of the Ca.sup.2+ from a .about.100 ppm Ca.sup.2+ solution at
a loading of 3 g per liter, and having either a stuffed silica
polymorph-related structure or a layered structure with a characteristic
broad X-ray powder diffraction peak occurring at a d-spacing of between 11
and 17 .ANG.. Central to the present invention is the discovery that some
stuffed silica polymorph-related magnesiosilicates, particularly those
that are imperfectly crystallised and possess substantial disordering of
the framework cations, and magnesiosilicates having a layered structure
with a characteristic broad X-ray powder diffraction peak occurring at a
d-spacing of between 11 and 17 .ANG., preferably between 12 and 16 .ANG.,
can have a significant calcium binding capacity (CBC). magnesium binding
capacity (MBC) and a relatively high calcium binding rate (CBR) in aqueous
solution. For the purposes of the present invention CBC is expressed in
units of mg CaO per gram of anhydrous magnesiosilicate and MBC is
expressed in units of mg MgO per gram of anhydrous magnesiosilicate, both
at room temperature. Advantageously, the compounds of the invention may
have a CBC of at least 20, preferably at least 50 and in many embodiments
at least 100. Advantageously, the compounds of the invention may have an
MBC of at least 15, preferably at least 40 and in many embodiments at
least 90. When well-prepared, these new compounds may have a CBC of at
least 150 and/or an MBC of at least 140. For the purposes of the present
invention, CBR is expressed in terms of the time taken to remove half of
the Ca.sup.2+ from a .about.100 ppm Ca.sup.2+ solution at room
temperature at a loading of3 g per liter. Advantageously, compounds of the
invention may have a CBR of no more than 200 seconds, preferably no more
than 100 seconds, more preferably no more than 50 seconds, even more
preferably no more than seconds, and most preferably no more than 10
seconds.
The compounds of the invention advantageously also have an oil absorption
(OA) of at least 50 g oil per 100 g of anhydrous material, preferably at
least 70 g oil, more preferably at least 100 g oil per 100 g of anhydrous
material.
Methods for determining CBC, MBC, CBR and OA are described hereinafter.
The magnesiosilicate compounds of the invention may be characterised in
terms of their composition, which may, in anhydrous form of the compounds,
be given by M.sub.a Mg.sub.b Al.sub.c Si.sub.1-(b+c) O.sub.d, where
M=alkali, optionally partially substituted by H or NH.sub.4 ; where
0.0<a<2.0, 0.0<b<0.7, 0.0.ltoreq.c.ltoreq.0.3, and 1.15<d<3.0, where c<b;
where there may be partial substitution of the atoms (Mg+Al+Si) by one or
more other elements T selected from the group B, Be, Zn, Ga, Fe, Ge, As
and P such that T/(Mg+Al+Si)<0.1 and Mg is >0; where there may be partial
substitution of the interstitial atoms M by one or more other elements A
selected from the group alkaline earth, transition metal and rare earth
elements such that A/M<0.2; and where impurity minerals or compounds which
are not integrated into the structure are not accounted for in the
composition. Such impurity minerals or compounds may include, for example,
TiO.sub.2 -anatase and SiO.sub.2 -quartz.
Preferably, 0.4<a<1.4, 0.2<b<0.6, 0.0.ltoreq.c.ltoreq.0.2, and 1.5<d<2.5;
and where T/(Mg+Al+Si)<0.05. More preferably 0.6<a<1.3, 0.35<b<0.6,
0.0.ltoreq.c.ltoreq.0.1, and 1.65<d<2.25; and where T/(Mg+Al+Si)<0.02.
Advantageously, Mg/Ca.ltoreq.100 and Si/(Mg+Ca)<1.4.
As is clear from the composition above, the interstitial cations may be
K.sup.+ or Na.sup.+, as in the compounds Na.sub.2 MgSiO.sub.4, Na.sub.4
Mg.sub.2 Si.sub.3 O.sub.10, K.sub.2 MgSiO.sub.4, and KMg.sub.0.5
Si.sub.1.5 O.sub.4, or it may be another alkali cation, such as Li.sup.+,
Rb.sup.+ or Cs.sup.+. The alkali cations may be partially substituted by
one or more other monovalent cations, such as NH.sub.4.sup.+ or H.sup.+.
These materials may also be prepared such that a small proportion of the
monovalent interstitial cations is substituted by polyvalent cations, such
as alkaline earth, transition metal and rare earth cations. The
interstitial sites may be occupied by a mixture of any two or more of the
aforementioned cations. However, alkali metal cations are the preferred
cations, in particular Na.sup.+ or K.sup.+.
It is believed that unreacted reagent anions which may be used in the
synthesis of magnesiosilicate compounds in accordance with the invention,
for example bicarbonate, carbonate, carboxylate, nitrate and hydroxide,
are not integrated into the structures, and it is for this reason they are
not included in the empirical composition above.
As described below, compounds in accordance with the invention may be made
by aqueous routes, but we have discovered that advantageously such
compounds having a stuffed silica polymorph-related structure may be
readily made by solid state reaction routes. Thus, also according to the
present invention, there is provided a process for the preparation of a
magnesiosilicate compound in accordance with the invention and having a
stuffed silica polymorph-related structure, which comprises subjecting a
magnesiosilicate starting material, or a combination of magnesium oxide-
and silicon oxide-containing reagents, to a solid state reaction with an
alkali oxide-containing reagent.
A variety of synthetic solid state reaction methods is available for use in
the above process, and some of these methods in which the interstitial
cation is an alkali metal cation are described below. These reaction
methods are preferably performed at a temperature of about 1000.degree. C.
or less, more preferably at a temperature in the range of about
450.degree. C. to about 800.degree. C. Temperatures greater than
1000.degree. C. may be used to achieve reaction, but the time of reaction
would necessarily be reduced to prevent the formation of well
crystallised, ordered materials with a CBR>300 seconds. Advantageous to
the successful synthesis of magnesiosilicate compounds in accordance with
the invention and having a stuffed silica polymorph-related structure, are
reactive starting materials, that is components or component precursors
which facilitate reaction at the above relatively low temperatures. The
relatively mild reaction conditions result in the formation of less well
crystallised materials with substantial disordering of the framework
cations, and it is this feature which is believed to lead to the
relatively high CBR in the stuffed silica polymorph-related compounds of
the invention.
Preferably, the magnesiosilicate compounds in accordance with the invention
with a layered structure have their characteristic broad X-ray powder
diffraction peak occurring at a d-spacing of from about 12 to about 16
.ANG..
Advantageously, the magnesiosilicate compounds according to the invention
and having a layered structure are formed by an aqueous route and in one
such route according to the invention the process comprises subjecting a
magnesiosilicate starting material, or a combination of magnesium oxide-
and silicon oxide-containing reagents, to aqueous reaction with an alkali
oxide-containing reagent.
These reaction methods are preferably performed in a temperature range of
from about 100.degree. C. to about 300.degree. C. in a sealed vessel, more
preferably in a temperature range of from about 150.degree. C. to about
200.degree. C. Temperatures greater than 300.degree. C. and/or elevated
pressures may be used to achieve reaction, but the time of reaction would
necessarily be reduced to ensure a compound in accordance with the
invention is produced.
Advantageous to the successful synthesis of magnesiosilicate compounds
having a layered structure in accordance with the invention are reaction
starting materials, that is components or component precursors which
facilitate reaction at the above relatively low temperatures.
To facilitate relatively mild reaction conditions for the formation of
these magnesiosilicate compounds in accordance with the invention having
either a stuffed silica polymorph-related structure or the layered
structure by the processes described above, it is particularly
advantageous to use a magnesiosilicate mineral starting material, which,
by definition, contains magnesium and silicon atoms mixed on the unit
cell, that is the nanometer, scale. With a high surface area and the
preferred relatively mild reaction conditions, the magnesiosilicate
minerals can lead to the formation of reactive, high surface area
magnesiosilicate compounds in accordance with the invention having very
high CBRs.
Magnesiosilicate phyllosilicates are, in general, suitable starting
materials for the formation of these compounds. For the purposes of the
present invention magnesiosilicate phyllosilicates are defined as
phyllosilicates having more magnesium than aluminium in their composition
and are thereby distinguished from aluminosilicate phyllosilicates
containing some magnesium.
Such magnesiosilicate phyllosilicates include the clay mineral saponite, as
well as the minerals talc and chrysotile. Most preferably, the
phyllosilicate is saponite or talc. While there is a significant range in
the silicon and magnesium contents of these starting materials, all are
considered, to a greater or lesser extent, to be a suitable source of
mnagnesiosilicate in the synthesis of the crystalline magnesiosilicates
having either a stuffed silica polymorph-related structure or the layered
structure.
One of the other advantages that mineral magnesiosilicates have as reactive
starting materials is their high natural abundance and relatively low unit
cost.
Various alkali salts and hydroxides are suitable reactive starting
materials which provide a source of the alkali cations. Most alkali salts
which decompose upon heating to 1000.degree. C. to give alkali oxide are
suitable. Alkali halides and alkali sulfides are not suitable.
It is also possible to use reactive forms of silica, such as silica gel and
colloidal silica, in combination with reactive forms of magnesium, such as
magnesium nitrate hexahydrate or magnesium basic carbonate, to provide the
source of magnesiosilicate for use in the above processes of the
invention.
We have also discovered that magnesiosilicate compounds in accordance with
the invention and having the layered structure can be formed by aqueous
routes from magnesiosilicate compounds having a stuffed silica
polymorph-related structure.
Thus, further according to the present invention there is provided a
process for the preparation of a magnesiosilicate compound in accordance
with the invention and having the layered structure, which comprises
treating a magnesiosilicate compound having a stuffed silica
polymorph-related structure with aqueous solution.
The aqueous solution used in this rinsing treatment may be distilled water
or it may be, for example, water containing small or large amounts of
dissolved species, such as Na.sup.- -containing solution. The treatment
process leads to a change in composition relative to the starting
material, for example such that the M/Mg ratio is reduced significantly
and the Si/Mg ratio is reduced slightly.
Preferably, the magnesiosilicate compound having a stuffed silica
polymorph-related structure is in accordance with the invention.
This process may be performed at room temperature. In a preferred
embodiment the magnesiosilicate compound having a stuffed silica
polymorph-related structure is dispersed in the aqueous solution, and
residual solid is separated from the supernatant liquid and dried. The
dispersing and separating steps may take no more than about minutes,
preferably no less than about 10 minutes. The separated residual solid may
be dried at less than about 100.degree. C. preferably less than about
60.degree. C. The separating step may be, for example, by centrifuging or
by filtration.
Still further according to the present invention, there is provided the use
of a magnesiosilicate compound in accordance with the invention as a water
softener and/or as a detergent builder.
Yet still further according to the present invention, there is provided a
detergent composition containing a magnesiosilicate compound in accordance
with the invention and a surfactant.
Also still further according to the present invention, there is provided a
moulded body comprising magnesiosilicate compound in accordance with the
invention, optionally further comprising a binder. Such a moulded body may
be a convenient form of the magnesiosilicate compound for use as a water
softener.
BRIEF DESCRIPTION OF THE DRAWINGS
Various embodiments of the magnesiosilicates having a stuffed silica
polymorph related structure and their aqueous derivatives, uses for them
and processes for producing them will now be described by way of example
only with reference to the accompanying drawings, in which:
FIG. 1 shows polyhedral representations of high-cristobalite (SiO.sub.2)
and idealised Na.sub.2 MgSiO.sub.4, projected down the cubic <110>
direction;
FIG. 2 shows polyhedral representations of high-tridymite (SiO.sub.2) and
idealised KMg.sub.0.5 Si.sub.1.5 O.sub.4, projected down the <110>
direction; and
FIGS. 3 to 6 show XRD profiles of the subject magnesiosilicate compounds
a-m prepared according to Examples 1-13 respectively. XRD data were
collected using CuK.alpha. radiation.
Peaks due to impurity minerals or reaction byproducts are indicated by
asterisks.
DETAILED DESCRIPTION OF THE INVENTION
Structure and Composition of Magnesiosilicate Compounds in Accordance with
the Invention and Having a Stuffed Silica Polymorph-related Structure
Magnesiosilicate compounds having a stuffed silica polymorph-related
structure can be characterised in terms of their structure and
composition.
The structures of the various magnesiosilicate compounds having a stuffed
silica polymorph-related structure are characterised most definitively by
X-ray powder diffraction. When well prepared these compounds give X-ray
powder diffraction profiles which display diffraction peaks characteristic
of the stuffed silica polymorphs. Characteristic diffraction profiles for
the various magnesiosilicates having a stuffed silica polymorph related
structure can be seen in FIGS. 3 to 5 for compounds a-k of Examples 1 to
11 respectively. The corresponding tabulated information is given in Table
1.
Cristobalite-related sodium magnesiosilicates are characterised by the
presence of dominant X-ray powder diffraction peaks or groups of peaks
occurring simultaneously at a d-spacing of 4.30.+-.0.15 .ANG. and at a
d-spacing of 2.64.+-.0.22 .ANG.. These peaks or groups of peaks are
related to the 111 and 220 X-ray powder diffraction peaks, respectively,
of high cristobalite.
Cristobalite-related potassium magnesiosilicates are characterised by the
presence of a dominant X-ray powder diffraction peak or group of peaks
occurring at a d-spacing of 2.73.+-.0.15 .ANG. and a weaker peak or group
of peaks at a d-spacing of 4.44.+-.0.10 .ANG.. These peaks or groups of
peaks are related to the 220 and 111 X-ray powder diffraction peaks,
respectively, of high cristobalite.
Tridymite-related potassium magnesiosilicates are characterised by the
presence of a dominant X-ray powder diffraction peak occurring at a
d-spacing of 3.11.+-.0.20 .ANG.. This peak is related to the 202 X-ray
powder diffraction peaks of high tridymite.
The XRD profiles observed for magnesiosilicates having a stuffed silica
polymorph related structure are dependent on the choice of starting
reagents and reaction conditions. They are also sometimes complicated by
the presence of unreacted starting materials, reaction byproducts such as
MgO or Na.sub.2 SiO.sub.3 or impurity minerals, such as quartz, calcite,
dolomite and feldspar, when naturally-occurring components are used.
Both these magnesiosilicate compounds and the magnesiosilicate compounds in
accordance with the invention and having a layered structure described
below can be further characterised by their composition.
In the broadest embodiment the subject magnesiosilicates have a composition
range in anhydrous form given by M.sub.a Mg.sub.b Al.sub.c Si.sub.1-(b+c)
O.sub.d, (M=alkali, optionally partially substituted by H or
NH.sub.4),where 0.0<a<2.0, 0.0<b<0.7, 0.0.ltoreq.c.ltoreq.0.3, and
1.15<d<3.0. Also c<b. This general formula does not account for partial
substitution of the tetrahedral atoms (Mg+Al+Si) by other elements T
(where T=B, Be, Zn, Ga, Fe, Ge, As or P) which can occupy such positions
in a tetrahedral framework structures. In the broadest embodiment
T/(Mg+Al+Si)<0.1 and Mg>0. Neither does this general formula account for
partial substitution of the interstitial atoms M by other elements A
(where A=alkaline earth, transition metal or rare earth elements) which
can occupy such interstitial sites in the structures. In the broadest
embodiment A/M<0.2. Neither does the general formula account for impurity
minerals or compounds which are not integrated into the structure, e.g.
TiO.sub.2 -anatase, SiO.sub.2 -quartz.
In a more preferred embodiment the subject magnesiosilicates have a
composition range in anhydrous form given by M.sub.a Mg.sub.b Al.sub.c
Si.sub.1-(b+c) O.sub.d, where 0.4<a<1.4, 0.2<b<0.6,
0.0.ltoreq.c.ltoreq.0.2, 1.5<d<2.5, and c<b. In this more preferred
embodiment T/(Mg+Al+Si)<0.05, A/M<0.2 and Mg>0. Again, the general formula
does not account for impurity minerals or compounds which are not
integrated into the structure, e.g. TiO.sub.2 -anatase, SiO.sub.2 -quartz.
In the most preferred embodiment the subject magnesiosilicates have a
composition range in anhydrous form given by M.sub.a Mg.sub.b Al.sub.c
Si.sub.1-(b+c) O.sub.d, where 0.6<a<1.3, 0.35<b<0.6,
0.0.ltoreq.c.ltoreq.0.1, 1.65<d<2.25, and c<b. In this most preferred
embodiment Ti(Mg+Al+Si)<0.02, A/M<0.2 and Mg>0. Again, the general formula
does not account for impurity minerals or compounds which are not
integrated into the structure, e.g. TiO.sub.2 -anatase, SiO.sub.2 -quartz.
It is believed that unreacted reagent anions which may be used in the
synthesis of magnesiosilicate cation exchange compounds, for example,
carbonate, bicarbonate, nitrate, are also not integrated into the
structures, and it is for this reason that they are not included in the
empirical composition.
Composition analyses and derived formulae for magnesiosilicate compounds
having silica polymorph-related structures and prepared according to
Examples 1-11 are presented in Table 2.
TABLE 1
__________________________________________________________________________
Relative intensities and d-spacings of characteristic diffraction peaks
of stuffed silica polymorph
magnesiosilicate compounds a-k of Examples 1-11
Example No.
d I/I.sub.o
d I/I.sub.o
d I/I.sub.o
d I/I.sub.o
d I/I.sub.o
d I/I.sub.o
__________________________________________________________________________
1. 4.24
100
2.65
50 2.59
70
2. 4.23
100
2.62.sub.sh
40 2.59
80
3. 4.23
20
2.72
100
4. 3.12
100
5. 4.26
90
2.70.sub.sh
50 2.66
100
2.58
80
6. 4.24
100
2.70.sub.sh
40 2.65
80 2.59
80
7. 4.24
100
2.69.sub.sh
50 2.64
90 2.59
80
8. 4.24
100
2.70.sub.sh
50 2.64
90 2.58
100
9. 4.24
100
2.66.sub.sh
30 2.59
80
10. 4.32
50
4.24
40 2.72
50 2.64
100
2.59
60
11. 4.45
20
4.31
20 3.08
15 2.73
100
2.64
30
2.58
25
__________________________________________________________________________
sh = shoulder on main diffraction peak
TABLE 2
__________________________________________________________________________
Bulk anhydrous composition and derived formulae for subject
magnesiosilicates (or Examples 1-11 determined by EDS
Example 1
Example 2
Example 3
Example 4
Example 5
Example 6
Example 7
wt % wt % wt % wt % wt % wt % wt %
__________________________________________________________________________
SiO.sub.2
38.0 50.7 34.3 58.5 40.5 36.5 38.9
TiO.sub.2
0.0.dagger.
0.3 0.0.dagger.
0.0.dagger.
0.0.dagger.
0.5 0.0.dagger.
Al.sub.2 O.sub.3
4.4 5.3 3.3 0.3 2.5 3.8 4.4
Fe.sub.2 O.sub.3
1.1 2.3 2.4 0.0.dagger.
0.0.dagger.
0.0.dagger.
0.9
MgO 21.7 25.1 15.1 14.3 21.9 21.2 22.1
CaO 0.0.dagger.
1.1 0.5 0.0.dagger.
0.5 0.4 0.3
Na.sub.2 O
34.5 14.8 1.8 0.8 34.6 37.6 33.4
K.sub.2 O
0.3 0.4 42.6 26.1 0.0.dagger.
0.0.dagger.
0.0.dagger.
a 0.89 0.31 0.90 0.41 0.88 1.00 0.84
b 0.43 0.40 0.37 0.27 0.43 0.43 0.43
c 0.07 0.07 0.06 0.01 0.04 0.06 0.07
d* 1.98 1.72 2.05 1.93 1.99 2.04 1.96
__________________________________________________________________________
Example 8
Example 9
Example 10
Example 11
Example 12
Example 13
wt % wt % wt % wt % wt % wt %
__________________________________________________________________________
SiO.sub.2
36.5 49.4 33.7 27.5 43.1 46.4
TiO.sub.2
0.0.dagger.
0.0.dagger.
0.0.dagger.
0.0.dagger.
0.0.dagger.
0.0.dagger.
Al.sub.2 O.sub.3
3.9 5.5 0.0.dagger.
2.0 5.6 6.0
Fe.sub.2 O.sub.3
0.0.dagger.
1.5 4.1 0.8 0.9 0.0.dagger.
MgO 22.1 29.9 26.8 14.8 28.5 26.5
CaO 0.3 0.4 0.6 0.0.dagger.
0.5 0.7
Na.sub.2 O
37.2 13.2 34.8 16.1 21.3 20.5
K.sub.2 O
0.0.dagger.
0.0.dagger.
0.0.dagger.
38.9 0.0.dagger.
0.0.dagger.
a 0.98 0.25 0.91 1.56 0.45 0.43
b 0.44 0.44 0.54 0.42 0.46 0.42
c 0.06 0.06 0.00 0.05 0.07 0.08
d* 2.02 1.66 1.92 2.34 1.73 1.76
__________________________________________________________________________
*required by charge balance not analysed
.dagger.set to zero as < 2
Synthesis of Magnesiosilicate Compounds in Accordance with the Invention
and Having a Stuffed Silica Polymorph-related Structure
Two general processes for the synthesis of the subject magnesiosilicate
compounds having a stuffed silica polymorph-related structure are
described.
1. The first process involves solid state reaction of alkali salt and
magnesium-containing phyllosilicates. The range of conditions for the
successful formation of these magnesiosilicate compounds by this process
is dependent on the magnesium-containing phyllosilicate used.
While many alkali salts and alkali hydroxide and all magnesium-containing
phyllosilicates are suitable as starting materials for this process, we
exemplify the process using alkali carbonate and the phyllosilicate talc
which are among the preferred starting materials.
In the first process the mole ratio of alkali carbonate (M.sub.2 CO.sub.3)
to the talc (Mg.sub.3 Si.sub.4 O.sub.10 (OH).sub.2) is from 0.1 to 4.5:1.
The preferred mole ratio is in the range of 2 to 3:1.
Reaction is suitably carried out at an elevated temperature at atmospheric
pressure for a sufficient period of time to enable conversion to a
magnesiosilicate compound having a stuffed silica polymorph-related
structure. Initially, the talc and alkali carbonate are intimately mixed
then heated to between 450 and 800.degree. C. until all the talc has
reacted. At the lower end of the temperature range the likelihood of
residual starting materials being present in the produce increases. The
preferred conditions for this process are 550 to 700.degree. C. for a
period of between 0.5 and 24 hours. The resultant solid contains a
magnesiosilicate compound with a stuffed silica polymorph related
structure as the majority phase.
2. The second process involves solid state reaction of a reactive form of
silica, a magnesium salt and an alkali salt, after the components have
been mixed via a gel synthesis route.
The range of conditions for the successful formation of these
magnesiosilicate compounds by this process is primarily dependent on the
magnesium and alkali salts used.
While many magnesium and alkali salts and reactive forms of silica are
suitable as starting materials for this process, we exemplify the process
using alkali nitrate, magnesium nitrate and colloidal silica which are
among the preferred starting materials.
In the second process, the mole ratios of colloidal silica
(.about.SiO.sub.2) to magnesium nitrate (Mg(NO.sub.3).sub.2) to alkali
nitrate (MNO.sub.3) are typically about 1:12, but can vary substantially
from this within the composition range described earlier. It is possible
to replace the colloidal silica by other forms of silica such as soluble
alkali silicate.
Reaction takes place by dissolving the magnesium and alkali nitrate in a
small amount of water, then adding the colloidal silica to the dissolved
salts. The reaction mixture is homogenised, then the water is evaporated
slowly, giving a gel. This gel is then further reacted at elevated
temperature and atmospheric pressure for a sufficient period of time to
enable conversion to magnesiosilicate compounds having a stuffed silica
polymorph-related structure in accordance with the invention. The gel is
heated to between 450.degree. C. and 800.degree. C. until magnesiosilicate
compound having a stuffed silica polymorph related structure is observable
by XRD. The preferred conditions for this process are 550.degree. C. to
700.degree. C. for a period of between 2 days and 6 hours.
Examples of Specific Conditions of Synthesis of Magnesiosilicate Compounds
in Accordance with the Invention and Having a Stuffed Silica
Polymorph-related Structure
Examples of the specific conditions of synthesis under which the components
react together to give magnesiosilicates having a stuffed silica polymorph
related structure are given below.
1. 200 g of .ltoreq.25 .mu.m talc is dispersed in 0.53 liters of water. A
solution containing 170 g of commercial grade Na.sub.2 CO.sub.3 in 0.50
liters of water is slowly added and the resultant slurry stirred
vigorously for 20 minutes. This slurry is then dehydrated using a spray
drier with an inlet temperature of 250.degree. C. The spray dried reaction
mixture is then heated at 600.degree. C. for 16 hours. The XRD profile of
this material, which has a cristobalite-related structure, is shown in
FIG. 3 (compound a).
2. 500 g of saponite from Watheroo, Western Australia, is dispersed in 2.0
liters of water A solution containing 330 g of commercial grade Na.sub.2
CO.sub.3 in 0.75 liters of water is slowly added and the resultant slurry
stirred vigorously for 20 minutes. This slurry is then dehydrated using a
spray drier with an inlet temperature of 250.degree. C. The spray dried
reaction mixture is then heated at 550.degree. C. for 3.5 hours. The
profile of this material which has a cristobalite-related structure is
shown in FIG. 3 (compound b).
3. 5.737 g of potassium nitrate is dissolved in 5 ml of water at 50.degree.
C. This solution is added to 5 g of saponite from Watheroo, Western
Australia, and thoroughly homogenised using a mortar and pestle then
dehydrated at 100.degree. C. The reaction mixture is then heated at
600.degree. C. for 21 hours. The XRD profile of this material which has a
simple cubic cristobalite-related structure is shown in FIG. 3 (compound
c).
4. 3.214 g of potassium nitrate and 4.07 g of magnesium nitrate hexahydrate
are dissolved in 10 ml of water at 50.degree. C. This solution is added to
8.98 g of Ludox AM (du Pont) colloidal silica (31.9 wt % SiO.sub.2). A gel
forms immediately upon mixing which is then dehydrated at 130.degree. C.
The dry mixture is then heated to 800.degree. C. for 2 days. The XRD
profile of this material which has a tridymite-related structure is shown
in FIG. 3 (compound d).
5. Material was prepared as for Example 1 except that a .ltoreq.20 .mu.m
talc was used as starting material. The XRD profile of this material,
which has a cristobalite-related structure, is shown in FIG. 4 (compound
e).
6. 200 g of partly delaminated talc, with specific surface of 18 m.sup.2
g.sup.-1, is dispersed in 0.6 liters of water. A solution containing 170 g
of commercial grade Na.sub.2 CO.sub.3 in 0.60 liters of water is slowly
added and the resultant slurry stirred vigorously for minutes. This slurry
is then dehydrated using a spray drier with an inlet temperature of
275.degree. C. The spray dried reaction mixture is then heated at
550.degree. C. for 16 hours. The XRD profile of this material, which has a
cristobalite-related structure, is shown in FIG. 4 (compound f).
7. 100 g of partly delaminated talc, with specific surface of 18 m.sup.2
g.sup.-1, is dispersed in 0.3 liters of water. A solution containing 68 g
of commercial grade Na.sub.2 CO.sub.3 in 0.24 liters of water is slowly
added and the resultant slurry stirred vigorously for minutes. This slurry
is then dehydrated using a spray drier with an inlet temperature of
275.degree. C. The spray dried reaction mixture is then heated at
550.degree. C. for 16 hours. The XRD profile of this material, which has a
cristobalite-related structure, is shown in FIG. 4 (compound g).
8. 120 g of ball milled talc, with specific surface of 45 m.sup.2 g.sup.-1,
is dispersed in 0.36 liters of water. A solution containing 102 g of
commercial grade Na.sub.2 CO.sub.3 in 0.36 liters of water is slowly added
and the resultant slurry stirred vigorously for 20 minutes. This slurry is
then dehydrated using a spray drier with an inlet temperature of
275.degree. C. The spray dried reaction mixture is then heated at
550.degree. C. for 16 hours. The XRD) profile of this material, which has
a cristobalite-related structure, is shown in FIG. 4 (compound h).
9. 200 g of .ltoreq.25 .mu.m talc is dispersed in 0.5 liters of water. A
solution containing 85 g of commercial grade Na.sub.2 CO.sub.3 in 0.25
liters of water is slowly added and the resultant slurry stirred
vigorously for 20 minutes. This slurry is then dehydrated using a spray
drier with an inlet temperature of 250.degree. C. The spray dried reaction
mixture is then heated at 600.degree. C. for 16 hours. The XRD profile of
the reaction product contains a mixture of cristobalite-related structures
and a small quantity of unreacted talc, shown in FIG. 5 (compound i)
10. 0.5 g of chrysotile, with nominal composition Mg.sub.3 Si.sub.2 O.sub.5
(OH).sub.4, is reacted with 0.6 g of sodium carbonate by thoroughly
grinding the solids together then reacting the mixture at 500.degree. C.
for 16 hours. The reaction product is then reground and reacted at
650.degree. for 4 days, then at 800.degree. C. for a further 4 days. The
XRD profile of the reaction product which shows a cristobalite-related
structure as the main phase, as well as some MgO, is shown in FIG. 5
(compound j).
11. 100 g of partly delaminated talc, with specific surface of 18 m.sup.2
g.sup.-1, is dispersed in 0.3 liters of water. A solution containing 42.5
g of commercial grade Na.sub.2 CO.sub.3 and 66.2 g of commerical grade
K.sub.2 CO.sub.3.1.5H.sub.2 O in 0.24 liters of water is slowly added and
the resultant slurry stirred vigorously for 20 minutes. This slurry is
then dehydrated using a spray drier with an inlet temperature of
275.degree. C. The spray dried reaction mixture is then hated at
500.degree. C. for 16 hours. The XRD profile of this material, which has a
cristobalite-related structure, is shown in FIG. 5 (compound k).
Structure and Composition of Magnesiosilicate Compounds in Accordance with
the Invention Having the Layered Structure
The structures of these magnesiosilicate compounds having a layered
structure are characterised most definitively by X-ray powder diffraction.
When well prepared they give X-ray powder diffraction profiles which
display a characteristic broad diffraction peak corresponding to a
d-spacing of between 11 and 17 .ANG.. Examples of characteristic
diffraction profiles for these compounds can be seen in FIG. 6 for
compounds 1 and m of Examples 12 and 13 respectively. Preferably, the
characteristic broad diffraction peak corresponds to a d-spacing of
between 12 and 16 .ANG..
The compositions of these magnesiosilicate compounds in accordance with the
invention having the layered structure are as described above for the
magnesiosilicate compounds having a stuffed silica polymorph-related
structure.
Composition analyses and derived formulae for magnesiosilicate compounds l
and m having the layered structure and prepared according to Example 12
and 13 respectively are presented in Table 2.
Synthesis of Magnesiosilicate Compounds in Accordance with the Invention
and Having the Layered Structure
Two general processes for the synthesis of the subject magnesiosilicate
compounds having the layered structure are described.
1. The first process comprises treating a magnesiosilicate compound with a
stuffed silica polymorph structure with water, whereby the starting
compound is dispersed in water for a time, the remaining solid then being
separated by centrifuge or by filtration from the supernatant liquid then
dried.
The preferred duration of this treatment is less than about 20 minutes, and
preferably less than about 10 minutes, with the drying of the resultant
solid product taking place at less than about 100.degree. C., and
preferably less than about 60.degree. C.
The water used in rinsing may be distilled water or it may be water
containing small or large amounts of dissolved species, such as an
Na.sup.+ -containing solution. The rinsing process leads to a change in
composition relative to the starting material such that the Na/Mg ratio is
reduced significantly and the Si/Mg ratio is reduced slightly. However,
the resulting composition remains within the broad composition described
above.
2. The second process comprises subjecting a magnesiosilicate material
starting material, or a combination of magnesium oxide- and silicon
oxide-containing reagents, to aqueous reaction with an alkali
oxide-containing reagent.
The reaction is performed at a temperature between 100 and 300.degree. C.
in a sealed vessel, and preferably between 150 and 200.degree. C.
The alkali oxide-containing reagent preferably decomposes in air at a
temperature below about 1000.degree. C. to give alkali oxide, and is more
preferably selected from one or more of the group bicarbonate, carbonate,
carboxylate, nitrate and hydroxide.
A preferred embodiment of the process is where the magnesiosilicate
starting material comprises a phyllosilicate mineral, and more preferably
where the phyllosilicate mineral is talc or saponite.
Examples of Specific Conditions of Synthesis of Magnesiosilicate Compounds
in Accordance with the Invention and Having the Layered Structure
An example of the first process for the synthesis of the magnesiosilicate
compounds having the layered structure is given below.
EXAMPLE 12
1.0 g of the material prepared according to Example 6 is dispersed in 40 ml
of distilled water and then centrifuged to separate the solid from the
supernatant liquid, the full procedure taking about 10 minutes. The solid
is then dried at 40.degree. C., yielding 0.82 g of white powder. The XRD
profile of the magnesiosilicate compound, which shows a dominant, broad
peak at a d-spacing of .about.12.5 .ANG. and remnant peaks due to the
stuffed silica polymorph related structure of the starting material, is
shown in FIG. 6 (compound l).
An example of the second process for the synthesis of the magnesiosilicate
compounds having the layered structure is given below.
EXAMPLE 13
1.483 g of NaOH is dissolved in 3 ml of water followed by the addition of
3.703 g of sodium silicate solution. The combined solution is then added
to 1.264 g of talc in a mortar and pestle and thoroughly ground, producing
a thick slurry. This slurry is then placed in a teflon-lined sealed
pressure vessel and heated at 185-190.degree. C. for 1 week. The resultant
solid is then removed from the vessel and rinsed with .about.50 ml of
water. The solid is then dried at 40.degree. C. The XRD profile of the
magnesiosilicate compound, which shows a dominant, broad peak at a
d-spacing of .about.15.0 .ANG. and remnant sharp peaks due to unreacted
chlorite from the starting material, is shown in FIG. 6 (compound m).
Preparation of a Monolithic Body
For some applications of the magnesiosilicate compounds in accordance with
the invention, particularly for use as a water softener, it may be
desirable to prepare a monolithic body. This can be achieved for those
compound formed by the solid state reaction route by pressing the dry
reaction mixture into its desired form prior to the solid state reaction.
A robust, porous body can be produced in this manner. A binder may be
included to further enhance the robustness of the body.
One Embodiment of Such a Process is Described in Example 14
EXAMPLE 14
1 g of spray dried reaction mixture described in Example 1 is pressed into
a monolithic form using a uniaxial press at a pressure of 2000 kgcm.sup.-2
for 3 minutes. The resultant pellet is then reacted at 650.degree. C. for
16 hours, producing a robust pellet with 52% of theoretical density.
Calcium Binding Capacity
For the purposes of the present invention two different methods were used
to determine calcium binding capacity (CBC). Calcium binding capacity is
measured as milligrams of CaO taken up per gram of the magnesiosilicate
compound at room temperature.
Method A
To characterise the magnesiosilicate compounds in accordance with their
proposed utility as water softeners or detergent builders, a method
similar to that described in GB 1 473 201 (Henkel) and EP 0 384 070 A2
(Unilever) was used. In this test 0.1 g of test compound was dispersed in
100 ml of 10 an aqueous solution containing 202 ppm of Ca.sup.2+, and
where necessary, adjusted to a pH of with dilute NaOH. The suspension was
stirred at 20.degree. C. for 15 minutes, then centrifuged to remove the
solid. The aqueous solution was then tested for residual Ca.sup.2+ using
a calcium-selective electrode.
Various examples of the subject magnesiosilicate compounds and, for
comparison, other commercially produced detergent builders were tested.
The results of these tests are given in Table 3 below. All of the
magnesiosilicate compounds of Examples 1 to 14 above have a CBC of greater
than 10 mg CaO at room temperature.
TABLE 3
______________________________________
Residual Ca.sup.2+ concentration and derived CBC using Method A*
Derived CBC
Material Ca.sup.2+ conc. (ppm)
(mg CaO/g)
______________________________________
Example 1 133.6 96.0
Example 5 133.6 96.0
Example 6 81.3 169.2
Example 7 96.3 145.4
Example 8 84.0 165.4
Zeolite P (EP 0 565 364 A1)
81.3 169.2
Zeolite 4A (Wessalith P, Degussa)
92.8 153.1
Zeolite 4A (Valfor, PQ Corp.)
78.0 173.9
SKS-6 (Hoechst) 66.7 186.9
______________________________________
*Initial Ca.sup.2+ concentration of 202.2 ppm, equivalent to 282.9 mg
CaO/g at loading of 0.1 g per 100 ml.
Method B
Calcium binding capacities were also compared in the presence of background
0.01 M Na.sup.+ in a manner similar to the method described in EP 0 384
070 A2 (Unilever) for the purpose of more closely simulating a wash liquor
environment. In this test 0.1 g of compound was dispersed in 100 ml of an
0.01 M NaCl solution containing 202 ppm of Ca.sup.2+, and where necessary,
adjusted to a pH of 10 with dilute NaOH. The suspension was stirred at
20.degree. C. for 15 minutes, then centriged to remove the solid. The
aqueous solution was then tested for residual Ca.sup.2+ using a
calcium-selective electrode.
Various examples of the subject magnesiosilicate compounds and, for
comparison, other commercially produced detergent builders were tested.
The results of these tests are given in Table 4 below.
TABLE 4
______________________________________
Residual Ca.sup.2+ concentration and derived CBC using Method B*
Derived CBC
Material Ca.sup.2+ conc. (ppm)
(mg CaO/g)
______________________________________
Example 1 131.2 99.2
Example 5 121.1 113.4
Example 6 65.9 190.5
Example 7 102.6 136.6
Example 8 73.8 179.5
Zeolite P (EP 0 565 364 A1)
91.7 154.4
Zeolite 4A (Wessalith P, Degussa)
86.3 162.0
Zeolite 4A (Valfor, PQ Corp.)
100.0 142.8
SKS-6 (Hoechst) 83.4 163.5
______________________________________
*Initial Ca.sup.2+ concentration of 202.2 ppm, equivalent to 282.9 mg
CaO/g at loading of 0.1 g per 100 ml.
Magnesium Binding Capacity
Magnesium binding capacity is measured as milligrams of MgO taken up per
gram of the magnesiosilicate compound at room temperature.
Method C
To characterise the magnesiosilicate compounds further in accordance with
their proposed utility as water softeners or detergent builders, a method
C similar to Method A described above was used to measure magnesium
binding capacity (MBC). In this test 0.1 g of test compound was dispersed
in 100 ml of an aqueous solution containing 200 ppm of Mg.sup.2+ and,
where necessary, adjusted to a pH of 10 with dilute NaOH. The suspension
was stirred at 20.degree. C. for 15 minutes, then centrifuged to remove
the solid. The aqueous solution was then tested for residual Mg.sup.2+
using atomic absorption spectroscopy.
Various examples of the subject magnesiosilicate compounds and, for
comparison, other commercially produced detergent builders were tested.
The results of these tests are given in Table 5 below. All of the
magnesiosilicate compounds of Examples 1 to 14 above have an MCB of
greater than 10 mg MgO at room temperature.
TABLE 5
______________________________________
Residual Mg.sup.2+ concentration and derived MBC using Method C
Derived MBC
Material Mg.sup.2+ conc. (ppm)
(mg MgO/g)
______________________________________
Example 1 168 53.1
Example 5 167 54.7
Example 6 112 145.9
Example 7 102 162.5
Example 8 82 195.7
Zeolite P (EP 0 565 364 A1)
198 3.3
Zeolite 4A (Wessalith P, Degussa)
174 43.1
Zeolite 4A (Valfor, PQ Corp.)
178 36.5
SKS-6 (Hoechst) 77 204.0
______________________________________
*Initial Mg.sup.2+ concentration of 200 ppm, equivalent to 331.7 mg MgO/g
at loading of 0.1 g per 100 ml.
Calcium Binding Rate (CBR)
Calcium binding rate is measured as the time taken to remove half of the
Ca.sup.2+ from approximately a 100 ppm Ca.sup.2- solution at room
temperature at a loading of 3 g of the magnesiosilicate compound per
liter.
Method D
The subject magnesiosilicate compound are further characterised in terms of
their calcium binding rate (CBR) in accordance with their utility as water
softeners or detergent builders To quantify the rate at which Ca.sup.2+
is removed from solution, using method D, 0.15 g of test compound is
dispersed in .about.1 ml of water which is then injected into 50 ml of
stirred solution containing 0.01 M NaCl, 0.1 M KCl and .about.100 ppm of
Ca.sup.2- concentration of the stirred solution is measured as a function
of time using a calcium selective electrode.
Various examples of the subject magnesiosilicate compounds and, for
comparison, other commerically produced detergent builders were tested.
The results of these test are given in table (6). All of the
magnesiosilicate compounds of Examples 1 to 13 above have a CBR of less
than 300 seconds at room temperature.
TABLE 6
______________________________________
Calcium binding rate according to Method D.
Material Time (seconds).dagger.
______________________________________
Example 1 5.0
Example 2 270
Example 5 4.5
Example 6 1.5
Example 7 10.0
Example 8 2.5
Example 11 12.0
Example 12 9.5
Zeolite P (EP 0 565 364 A1)
14.5
Zeolite 4A (Wessalith P, Degussa)
11.5
Zeolite 4A (Valfor, PQ Corp.)
11.5
SKS-6* (Hoechst) 250
______________________________________
.dagger. time to remove half of the Ca.sup.2+ from solution.
*material added dry due to inability to disperse in 1 ml of water
Oil Absorption (OA)
Oil absorption was determined by the ASTM spatula rub-out method D281 as
also used in EP 0 565 364 A1. This test is based on the principle of
mixing linseed oil with the particulate material by rubbing with a spatula
on a smooth surface until a stiff putty-like paste is formed which will
not break or separate when it is cut with a spatula. The Oil Absorption
(OA) is expressed in grams of oil per 100 g of dry material.
Various examples of the subject magnesiosilicate compounds and, for
comparison, other commercially produced detergent builders were tested.
The results of these tests are given in Table 7 below.
TABLE 7
______________________________________
Oil Absorption results using ASTM method D281.
Sample OA Sample OA
______________________________________
Example 1
60-92 Zeolite P (EP 0 565 364 A1)
63-77
Example 5
102 Zeolite 4A (Valfor, PQ Corp.)
36-43
Example 6
107-113 Zeolite 4A (Wessalith P, Degussa)
60
Example 7
107 SKS-6 (Hoechst) 95
Example 8
77
Example 11
154
______________________________________
Use in Detergent Formulation
One example of the subject magnesiosilicate compounds was tested for its
utility as a detergent builder in comparison with the commercially used
materials, Zeolite 4A and sodium tripolyphosphate (STPP). The three
formulations tested are given in Table 8 below.
Other formulations incorporating the subject magnesiosilicate compounds may
be adopted for detergent compositions as will be readily understood by
those skilled in the detergency art. By way of example only, we direct
reference to the discussion on detergent compositions in EP-A-0384070 and
its United States equivalent (which are incorporated herein by reference)
which applies mutatis mutandis to detergent compositions incorporating the
subject magnesiosilicate compounds.
TABLE 8
______________________________________
Laundry detergent formulations used in comparative swatch tests.
Formulation A
Formulation B
Formulation C
STPP built
Zeolite 4A built
Ex. 1 built
______________________________________
Sodium tripoly-
15.0%
phosphate
Zeolite 4A 18.0%
Magnesiosilicate 18.0%
Ex. 1
Dense soda ash
25.0% 24.0% 5.3%
Sodium sulphate
31.4% 29.4% 48.1%
Coconut 2.5% 2.5% 2.5%
diethanalamide 1:1
Sodium dodecyl
15.0% 15.0% 15.0%
benzene suphonate
Sodium metasilicate
10.0% 10.0% 10.0%
(DMS) 0.1% 0.1% 0.1%
bis(triazinylamino)
stilbene di sulphonic
acid der.
______________________________________
Comparative Laundry Swatch Test Results
The comparative tests described below used a FOM 71 LAB front loading 7 kg
capacity washer-extractor. The three formulations as listed in Table 8
were dosed at 8 g/L with liters of water per wash.
The two swatches used were EMPA 105, which contained five regions (white,
carbon black/oil, blood, chocolate & milk, red wine) and white cotton.
Each of the two swatches was washed separately with each of the three
formulations A to C under four sets of conditions as follows:
1. Soft water (17 mg/L CaCO.sub.3) at 20.degree. C.
2. Hard water (135 mg/L CaCO.sub.3) at 20.degree. C.
3. Soft water (17 mg/L CaCO.sub.3) at 60.degree. C.
4. Hard water (135 mg/L CaCO.sub.3) at 60.degree. C.
Comparative results are listed in Tables 9 to 12 below giving visual
estimation of the colour of each region on each swatch and a ranking of
performance.
TABLE 9
__________________________________________________________________________
Soft water (17 mg/L CaCO.sub.3) at 20.degree. C.
EMPA 105 White Cotton
EMPA 105 Carbon Chocolate WHITE
Swatch No.
White
Black/Oil
Blood & Milk
Red Wine
Swatch No.
__________________________________________________________________________
Formulation A
1 = 1 1 1 pale fawn/
1 Formulation A
1
white
grey pale yellow
brown pale fawn white
Formulation B
= 2 = 1 3 deeper
2 pale fawn/
2 Formulation B
2 slightly
pale cream
grey yellow
brown pale fawn duller white
Formulation C
= 2 2 2 3 darker
3 slightly
Formulation C
3 duller
pale cream
mid grey
yellow
brown darker fawn white
Unwashed
Dull white
Pantone
Pantone
Pantone
Pantone
Unwashed
white
blank 423U 4635U 728U 4755U blank
slate grey
dark brown
coffee brown
fawn brown
__________________________________________________________________________
TABLE 10
__________________________________________________________________________
Hard water (135 mg/L CaCO.sub.3) at 20.degree. C.
EMPA 105 White Cotton
EMPA 105 Carbon Chocolate WHITE
Swatch No.
White
Black/Oil
Blood & Milk
Red Wine
Swatch No.
__________________________________________________________________________
Formulation A
1 1 1 1 pale
1 Formulation A
3
white
pale grey
pale cream
fawn/brown
pale fawn dull white
Formulation B
3 3 3 2 chocolate
2 Formulation B
1
off white
pale grey
deep cream
brown pale fawn white
Formulation C
2 2 2 3 chocolate
3 Formulation C
2
off white
pale grey
dark cream
brown darker fawn white
Unwashed
Dull white
Pantone
Pantone
Pantone
Pantone
Unwashed
white
blank 423U 4635U 728U 4755U blank
slate grey
dark brown
coffee brown
fawn brown
__________________________________________________________________________
TABLE 11
__________________________________________________________________________
Soft water (17 mg/L CaCO.sub.3) at 60.degree. C.
EMPA 105 White Cotton
EMPA 105 Carbon Chocolate WHITE
Swatch No.
White
Black/Oil
Blood & Milk
Red Wine
Swatch No.
__________________________________________________________________________
Formulation A
1 1 2 2 1 Formulation A
1 slightly
white
pale grey
pale fawn
red brown
pale fawn off white
Formulation B
3 2 3 1 2 Formulation B
= 2
cream
grey fawn pale brown
sandy off white
Formulation C
2 3 1 3 darker
3 Formulation C
= 2
cream
darker grey
pale fawn
brown brown off white
Unwashed
Dull white
Pantone
Pantone
Pantone
Pantone
Unwashed
white
blank 423U 4635U 728U 4755U blank
slate grey
dark brown
coffee brown
fawn brown
__________________________________________________________________________
TABLE 12
__________________________________________________________________________
Hard water (135 mg/L CaCO.sub.3) at 60.degree. C.
EMPA 105 White Cotton
EMPA 105 Carbon Chocolate WHITE
Swatch No.
White
Black/Oil
Blood & Milk
Red Wine
Swatch No.
__________________________________________________________________________
Formulation A
= 1 1 1 1 1 Formulation A
= 1
white
pale grey
pale fawn
pink ochre
pale fawn white
Formulation B
= 1 2 2 2 2 Formulation B
2
white
pale grey
pale fawn
pink ochre
sandy off white
Formulation C
2 3 3 3 chocolate
3 Formulation C
= 1
cream
dark grey
dark khaki
brown dark sand white
Unwashed
Dull white
Pantone
Pantone
Pantone
Pantone
Unwashed
white
blank 423U 4635U 728U 4755U blank
slate grey
dark brown
coffee brown
fawn brown
__________________________________________________________________________
These comparative results demonstrate that the subject magnesiosilicates
compare well with Na zeolite A and therefore have utility as
phosphate-free detergent builders.
Those skilled in the art will appreciate that the invention described
herein is susceptible to variations and modifications other than those
specifically described. It is to be understood that the invention includes
all such variations and modifications which fall within its spirit and
scope. The invention also includes all of the steps, features,
compositions and compounds referred to or indicated in this specification,
individually or collectively, and any and all combinations of any two or
more of said steps or features.
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